 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.internal.menus;

 /**
  * <p>
  * A reference to an already existing menu element. A reference is used to
  * modify or extend the meaning of an existing menu element.
  * </p>
  * <p>
  * Clients may instantiate this class, but must not extend.
  * </p>
  * <p>
  * <strong>PROVISIONAL</strong>. This class or interface has been added as
  * part of a work in progress. There is a guarantee neither that this API will
  * work nor that it will remain the same. Please do not use this API without
  * consulting with the Platform/UI team.
  * </p>
  * <p>
  * This class will eventually exist in <code>org.eclipse.jface.menus</code>.
  * </p>
  *
  * @since 3.2
  */
 public final class SReference {

     /**
      * The constant for a reference that refers to an unspecified type of menu
      * element.
      */
     public static final int TYPE_UNSPECIFIED = 0;

     /**
      * The constant for a reference that refers to a menu.
      */
     public static final int TYPE_MENU = 1;

     /**
      * The constant for a reference that refers to a group.
      */
     public static final int TYPE_GROUP = 2;

     /**
      * The constant for a reference that refers to an item.
      */
     public static final int TYPE_ITEM = 3;

     /**
      * The constant for a reference that refers to a widget.
      */
     public static final int TYPE_WIDGET = 4;

     /**
      * The type of reference. This must be one of the type constants given in
      * this class.
      */
     private final int type;

     /**
      * The identifier of the menu element this refers to. Must not be
      * <code>null</code>.
      */
     private final String id;

     /**
      * Constructs a new instance of <code>SReference</code>.
      *
      * @param type
      * The type of menu element this is making reference to. This
      * must be one of <code>TYPE_UNSPECIFIED</code>,
      * <code>TYPE_MENU</code>, <code>TYPE_GROUP</code>,
      * <code>TYPE_ITEM</code> or <code>TYPE_WIDGET</code>.
      * @param id
      * The identifier of the menu element this refers to; must not be
      * <code>null</code>.
      */
     public SReference(final int type, final String id) {
         if ((type < TYPE_UNSPECIFIED) || (type > TYPE_WIDGET)) {
             throw new IllegalArgumentException (
                     "The type of reference is not understood"); //$NON-NLS-1$
 }
         if (id == null) {
             throw new NullPointerException (
                     "The identifier of the menu element must be null"); //$NON-NLS-1$
 }

         this.type = type;
         this.id = id;
     }

     /**
      * Returns the identifier of the menu element to which this refers.
      *
      * @return The identifier of the menu element; never <code>null</code>.
      */
     public final String getId() {
         return id;
     }

     /**
      * Returns the type of reference. This will be one of the type constants in
      * this class.
      *
      * @return The type of reference.
      */
     public final int getType() {
         return type;
     }
 }

